Systematics/Phytogeography / Taxonomie/ Section
Cantino, P. D. .
The taxonomic treatment of hybrid derivatives under the ICBN and the PhyloCode.
By convention, ranked taxa must be either nested or mutually exclusive, but clades that include species of hybrid origin may be partially overlapping. Consequently, reticulate evolution presents a challenge for phylogenetic systematists using traditional rank-based taxonomy and nomenclature, where a species can belong to only one taxon at a given rank. Assignment of a species derived from an intersectional (or intersubgeneric or intergeneric) hybrid to only one of its parental sections (or subgenera or genera) renders the other parental taxon at the same rank paraphyletic. When classifying such hybrids using a ranked hierarchy, one must reject either the convention that an organism can only belong to one taxon at a given rank or the convention that paraphyletic groups should not be formally recognized. Phylogenetic nomenclature accurately reflects the complex patterns of descent that result from hybridization, in that a species of hybrid origin belongs to all of the named clades that contain each of its parents. Thus, the expectation that named supraspecific taxa be monophyletic is maintained in spite of hybridization. The infrageneric taxonomy of Pycnanthemum (Labiatae) is used to contrast the treatment of hybrid derivatives under the ICBN and the PhyloCode.
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1 - Ohio University, Department of Environmental & Plant Biology, Porter Hall, Richland Avenue, Athens, Ohio, 45701-2979, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Room 1/Woodward
Date: Monday, July 28th, 2008
Time: 4:00 PM